User interface for a portion of a display screen



The FIGURE is a front view of a user interface for a portion of a display screen showing our new design.

The broken lines on the right and left sides form an unclaimed boundary of the design. The broken line showing of the display screen is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 